Interface to full and reduce pin jtag devices

ABSTRACT

The disclosure describes a process and apparatus for accessing devices on a substrate. The substrate may include only full pin JTAG devices ( 504 ), only reduced pin JTAG devices ( 506 ), or a mixture of both full pin and reduced pin JTAG devices. The access is accomplished using a single interface ( 502 ) between the substrate ( 408 ) and a JTAG controller ( 404 ). The access interface may be a wired interface or a wireless interface and may be used for JTAG based device testing, debugging, programming, or other type of JTAG based operation.

CROSS REFERENCE TO RELATED PATENTS

This application is a divisional of prior application Ser. No.13/078,621, filed Apr. 1, 2011, currently pending;

-   Which was a divisional of prior application Ser. No. 12/883,629,    filed Sep. 16, 2010, now U.S. Pat. No. 7,945,832, granted May 17,    2011;-   which is a divisional of prior application Ser. No. 11/874,594,    filed Oct. 18, 2007, now U.S. Pat. No. 7,818,641, granted Oct. 19,    2010;-   which claims priority from Provisional Application No. 60/829,979,    filed Oct. 18, 2006.

FIELD OF THE DISCLOSURE

This disclosure relates to an interface for accessing full and reducedpin JTAG devices on a substrate.

BACKGROUND OF THE DISCLOSURE

Electrical devices, which may be boards, ICs or embedded cores withinICs, require JTAG interfaces to provide testing and debugging of thedevice's hardware and software designs. In the past, device test anddebug interfaces used the full pin JTAG interface consisting of TDI,TCK, TMS, TRST and TDO signal pins. The TRST pin is optional. Morerecently, reduced pin JTAG interfaces are being used for test and debugwhen device pins are not available for the full pin JTAG interface.Substrates, boards or ICs, containing both full and reduced pin JTAGdevices will therefore require a full pin JTAG interface for accessingthe full pin JTAG devices and a separate reduced pin JTAG interface foraccessing the reduce pin JTAG devices. Requiring both a full and reducedpin JTAG interface on substrates complicates test and debug operations.Ideally, and according to the disclosure, substrate test and debugoperations should be done without requiring the substrate to have both afull and reduced JTAG interface.

FIG. 1 illustrates an example of a full pin JTAG (FPJ) interface on adevice. Full pin JTAG (IEEE 1149.1) interfaces comprising a TDI, TCK,TMS, TRST and TDO signals are well known and broadly used in theindustry for testing, debugging, programming and/or other operations.

FIG. 2 illustrates an example of a reduced pin JTAG (RPJ) interface on adevice. Reduced pin JTAG interfaces are relatively new in the industryand typically comprised no more than one or two interface signals tocarry out test, debug, programming and/or other operations.

FIG. 2A illustrates an addressable type of RPJ interface that requires aclock (CLK) and a data I/O (DIO) signal. This type of RPJ interface isdescribed in detail in a 2006 IEEE International Test Conference paperby Whetsel titled “A High Speed Reduced Pin Count JTAG Interface”, whichis incorporated and referenced herein.

FIG. 2B illustrates another addressable type of RPJ interface thatrequires a clock (TCK) and a data I/O (TMSC) signal. This type of RPJinterface is the subject of developing IEEE standard P1149.7 anddescribed in a 2006 white paper titled “MIPI Test and Debug InterfaceFramework”, which is incorporated and referenced herein.

FIG. 2C illustrates a non-addressable type of RPJ interface thatrequires only a single I/O signal referred to as a JTAG Link (JLINK)signal. This JLINK interface was developed by DebugInnovation. The JLINKinterface is described on DebugInnovation's website, which isincorporated and referenced herein.

FIG. 2D illustrates a non-addressable type of RPJ interface thatrequires only a single I/O signal referred to as a Single Wire JTAG(SWJ) signal. This SWJ interface was developed by ARM Ltd. The SWJinterface is described on ARM's website, which is incorporated andreferenced herein.

While each of the addressable and non-addressable RPJ interfaces of FIG.2A-2D are operationally different, they can all be used to achieve a RPJinterface for device test, debug, programming and other operations.Throughout the remainder of this description the term RPJ interface isgeneral and can be used to reference any of the RPJ interfaces shown inFIGS. 2A-2D, as well as any other type of RPJ interface.

FIG. 3 illustrates a substrate 302, which can be a system, board or IC,that includes one or more FPJ (304) devices and one or more RPJ (306)devices. While plural FPJ devices 304 are shown in a daisy-chain, asingle FPJ device may exist as well. Further, while plural addressableRPJ devices 306 are shown bussed together, a single non-addressable RPJdevice 306 may exist as well. The devices 304-306 can be boards in asystem, ICs on a board, or cores within an IC. As seen the FPJ devices304 require a full pin JTAG interface 308 to a FPJ controller 310 andthe RPJ devices 306 require a separate reduced pin interface 312 to aseparate RPJ controller 314. Thus for test, debug, programming or otheroperations, the substrate 302 disadvantageously requires two separateJTAG interface 308 and 312 coupled to two separate JTAG controllers 310and 314.

The disclosure, as will be described in detail below, does not requiresubstrates 302 to have two separate JTAG interface 308 and 312 eachcoupled to two separate JTAG controllers 310 and 314. Advantageouslytherefore, the disclosure provides for substrate test, debug,programming and other operations to FPJ and RPJ devices to occur over asingle interface coupled to a single JTAG controller. In the followingdescription JTAG access FPJ or RPJ device interfaces includes accessrequired for device testing, device debug, device programming, or anyother operation performed using a FPJ or RPJ device interface.

BRIEF SUMMARY OF THE DISCLOSURE

The disclosure provides a process and apparatus for providing a singleJTAG controller to access FPJ and RPJ devices residing on a substrateusing only a single interface between the JTAG controller and substrate.

BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWINGS

FIG. 1 illustrates a full pin JTAG (FPJ) interface for accessing adevice.

FIG. 2 illustrates a reduced pin JTAG (RPJ) interface for accessing adevice.

FIG. 2A illustrates a device including a first known type of RPJinterface.

FIG. 2B illustrates a device including a second known type of RPJinterface.

FIG. 2C illustrates a device including a third known type of RPJinterface.

FIG. 2D illustrates a device including a fourth known type of RPJinterface.

FIG. 3 illustrates a substrate containing FPJ and RPJ devices interfacedto separate FPJ and RPJ controllers.

FIG. 4 illustrates a substrate containing FPJ and RPJ devices interfacedto a single JTAG controller via a FPJ & RPJ Interface according to thedisclosure.

FIG. 5 illustrates the FPJ & RPJ Interface of FIG. 4.

FIG. 6 illustrates the addressable JTAG interface of FIG. 5.

FIG. 7 illustrates the shadow protocol circuit of FIG. 6.

FIG. 8A illustrates the state diagram of an IEEE 1149. TAP statemachine.

FIG. 8B illustrates the state diagram of the shadow protocol detectioncircuit of FIG. 7.

FIG. 8C illustrates an example implementation of the shadow protocoldetection circuit of FIG. 7.

FIG. 8D illustrates an example implementation of the address circuit ofFIG. 7.

FIG. 8E illustrates an example implementation of the command circuit ofFIG. 7.

FIG. 9 illustrates the FPJ interface of FIG. 5.

FIG. 10 illustrates the RPJ interface of FIG. 5.

FIG. 10A illustrates the RPJ interface of FIG. 10 designed to adapt anFPJ interface into a number of separate SBT Based RPJ interfaces.

FIG. 10B illustrates the RPJ interface of FIG. 10 designed to adapt anFPJ interface into a number of separate IEEE P1149.7 RPJ interfaces.

FIG. 10C illustrates the RPJ interface of FIG. 10 designed to adapt anFPJ interface into a number of separate JLINK RPJ interfaces.

FIG. 10D illustrates the RPJ interface of FIG. 10 designed to adapt anFPJ interface into a number of separate SWJ RPJ interfaces.

FIG. 11 illustrates a substrate containing only FPJ devices interfacedto a single JTAG controller via a FPJ Only Interface according to thedisclosure.

FIG. 12 illustrates the FPJ Only Interface of FIG. 11.

FIG. 13 illustrates a substrate containing only RPJ devices interfacedto a single JTAG controller via a RPJ Only Interface according to thedisclosure.

FIG. 14 illustrates the RPJ Only Interface of FIG. 13.

FIG. 15 illustrates a system (substrate) of boards (devices), each boardcomprising FPJ and/or RPJ ICs which are accessed via the architecture ofthe disclosure.

FIG. 16 illustrates a board (substrate) of ICs (devices), each ICcomprising FPJ and/or RPJ cores which are accessed via the architectureof the disclosure

FIG. 17 illustrates an IC (substrate) of cores (devices), each corecomprising FPJ and/or RPJ sub-cores which are accessed via thearchitecture of the disclosure.

FIG. 18 illustrates the FPJ & RPJ access architecture of the disclosureadapted to utilize wireless communication between the substrate(system/board/IC) and JTAG controller.

FIG. 19 illustrates the FPJ Only access architecture of the disclosureadapted to utilize wireless communication between the substrate(system/board/IC) and JTAG controller.

FIG. 20 illustrates the RPJ Only access architecture of the disclosureadapted to utilize wireless communication between the substrate(system/board/IC) and JTAG controller.

DETAILED DESCRIPTION OF THE DISCLOSURE

FIG. 4 illustrates a substrate 402 that includes the FPJ and RPJ deviceaccess architecture of the disclosure. As seen, the architectureincludes an FPJ & RPJ Interface circuit 408 that is coupled to; (1) agroup 410 of FPJ devices 304 via FPJ interface 308, (2) a group 412 ofRPJ devices 306 via RPJ interface 312, and (3) a JTAG controller 404 viaa JTAG interface bus 406. Any number of groups 410 of one or more FPJdevices 304 may be coupled to JTAG controller 404 by separate FPJinterfaces 308. Any number of groups 412 of one or more RPJ devices 306may be coupled to JTAG controller 404 by separate RPJ interfaces 312.The JTAG controller 404 may access a group of one or more FPJ devices ora group of one or more FPJ devices by the FPJ & RPJ interface circuit408 via JTAG interface bus 406.

FIG. 5 illustrates in more detail the FPJ & RPJ Interface circuit 408 ofFIG. 4. As seen, circuit 408 comprises an addressable JTAG interface502, a FPJ interface 504, and a RPJ interface 506. The JTAG interface502 is coupled to a JTAG controller 404 via bus 406 which includes a TDI508, TCK 510, TMS 512, TRST 514, and TDO 516 signal. The TDI 508 signalprovides data input from the JTAG controller 404. The TCK 510 signalprovides clock input from the JTAG controller 404. The TMS 512 signalprovides control input from the JTAG controller 404. The TRST 514 signalprovides reset input from the JTAG controller 404. The TDO 516 signalprovides data output to the JTAG controller 404. The JTAG interface 502is coupled to the FPJ interface 504 via busses 518 and 520 and to RPJinterface 506 via busses 518 and 522. The FPJ interface 504 interfacesto one or more (N) FPJ device groups 410 via FPJ busses 308. The RPJinterface 506 interfaces to one or more (N) RPJ device groups 412 viaRPJ busses 312.

FIG. 6 illustrates the addressable JTAG interface 502 in more detail,which comprises a shadow protocol circuit 602, And gate 604, and 3-statebuffer 606. Addressable JTAG Circuit 602 inputs the TDI, TCK, TMS andTRST signals from bus 406 and outputs a select FPJ (SELFPJ) bus 520 toFPJ interface 504, a select RPJ (SELRPJ) bus 522 to RPJ interface 506,and an enable (ENA) signal 608 to And gate 604 and 3-state buffer 606.The SELFPJ bus 520 is used to select an FPJ device group 410 for access,the SELRPJ bus 522 is used to select an RPJ device group 412 for access,and the ENA signal 608 enables And gate 604 and 3-state buffer 606, toprovide for bus 406 to be fully coupled to bus 518. When bus 406 isfully coupled to bus 518, the selected FPJ 410 or RPJ 412 device groupmay be accessed by the JTAG controller 404 via bus 406.

FIG. 7 illustrates the shadow protocol circuit 602 in more detail, whichcomprises a shadow protocol detection circuit 702, command circuit 704,and address circuit 706. The shadow protocol detection circuit 602inputs the TDI, TCK, TMS and TRST signals from bus 406 and a matchsignal from address circuit 706. The detection circuit 702 outputs acommand input (CI) signal and command control signals (CC) to commandcircuit 704 and an address input (AI) signal and address control signals(AC) to address circuit 706. The command circuit 704 outputs the FPJSELbus 520 to FPJ interface 504 and the RPJSEL bus 522 to RPJ interface522.

When the JTAG controller 404 is in the RunTest/Idle state 802, thePause-DR state 804, or the Pause-IR state 806 of the IEEE 1149.1 TAPstate diagram 801 of FIG. 8A, the Detection circuit 702 is enabled torespond to a shadow protocol message 707 input on TDI to input addressdata to the address circuit 704 and command data to the command circuit706. If the JTAG controller 404 is not in one of these states 802-806,the detection circuit 702 is disabled from responding to the message707. The detection circuit and all FPJ and FPJ devices coupled to theFJP & RPJ interface 408 are reset by the TRST signal going low or by theJTAG bus 406 transitioning to the Test Logic Reset state of FIG. 8A.

The shadow protocol message 707 consists of a start field 708 comprisingan idle symbol (I) 718 and a select symbol (S) 720, an address field 710comprising a number of logic one or zero address symbols (A) 722 and724, a delimiter field 712 comprising a select symbol (S) 720, a commandfield 714 comprising a number of logic one or zero command symbols (C)722 and 724, and a stop field 716 comprising a select symbol (C) 720 andan idle symbol (I) 718. The symbols 718-724 are each defined by a pairof logic bits, with the I symbol 718 being two logic ones, the S symbol720 being two logic zeros, the logic zero A or C symbol 722 being alogic one followed by a logic zero, and the logic one A or C symbol 724being a logic zero followed by a logic one. As seen, the TCK times thesymbol bit pair inputs on TDI. If desired the symbol bit pairdefinitions may be defined differently from that shown in examples718-724.

FIG. 8B illustrates the state diagram 807 of the detection circuit 702.If the JTAG bus 406 is not in TAP states 802, 804, or 806, the detectioncircuit 702 will be in the idle state 808. If the JTAG bus 406 is instate 802, 804 or 806, the detection circuit 702 transitions to state810 to enable the detection of a shadow protocol message 707. If amessage start field 708 occurs in state 810 the detection circuit 702transitions to state 812 to input an address field 710 to the addresscircuit 704. When the delimiter field 712 occurs at the end of anaddress field input, the detection circuit transitions to state 814 toevaluate the match signal output from address circuit 706 to determineif the address input to the address circuit 704 matches the address ofthe FPJ & RPJ interface 408. If it does not match, the detection circuittransitions to and remains in state 810 for the remainder of the message707. If it does match, the detection circuit transitions to state 816 toenable the command circuit 706 for receiving a command field 714. Whenthe stop field 716 occurs at the end of the command field 714 input, thedetection circuit transitions to state 818 to output the command data onthe FPJSEL 520 and RPJSEL 522 busses to select an FPJ device group 410or an RPJ device group 412 for access and to output the ENA signal 608to fully couple busses 406 and 518. From state 818, the detectioncircuit 702 transitions to state 810. When the JTAG bus 406 transitionsout of state 802, 804 or 806 to resume JTAG operations, the detectioncircuit 702 returns to the idle state 808.

Following the above described shadow protocol message input 707, theselected FPJ 520 or RPJ 522 device group can be accessed bytransitioning through the states of the IEEE 1149.1 TAP state diagram801. When access to another FPJ 520 or RPJ 522 device group is desired,the above described process is repeated.

FIG. 8C illustrates an example implementation 820 of the shadow protocoldetection circuit 702, which consists of a state machine 822 and a TAPstate monitor 824. The TAP state monitor is basically an IEEE 1149.1 TAPthat is used to track the state of the JTAG bus 406. The TAP statemonitor 824 outputs a RST signal 827 and an Enable signal 826 to thestate machine 822. The TAP state monitor 824 outputs a low on RST 827whenever the JTAG bus 406 transitions to the Test Logic Reset state ofFIG. 8A. The TAP state monitor 824 outputs a high on the Enable signal826 to state machine 822 whenever the JTAG bus 406 is in theRunTest/Idle state, the Pause-DR state, or the Pause-IR state. If theEnable signal 826 is low the JTAG bus 406 is not in one of these statesand the state machine 822 will be forced to the idle state 808 of FIG.8B. If the enable signal 826 is high the JTAG bus 406 is in one of thesestates and the state machine 822 will transition to state 810 of FIG. 8Bto look for the start field 708 of a message 707.

When a message is started, state machine 822 will transition to state812 of FIG. 8B to decode the address symbols (A) input from TDI duringaddress input field 710 into logic one or zero bits and output thesebits on AI to the address circuit 706. The state machine outputs addresscontrol (AC) to the address circuit 706 to cause the AI bits to be inputto the address circuit 706. In response to detecting the delimiter field712 the state machine 822 will transition to state 814 to interpret theMatch signal from address circuit 706 as previously described. If anaddress match is detected, the state machine transitions to state 816 todecode the command symbols (C) input from TDI during command input field714 into logic one or zero bits and output these bits on CI to thecommand circuit 704. If an address match does not occur, state machine822 transitions to state 810 of FIG. 8B. A transition from state 814 tostate 810, as a result of an address mismatch, sets the ENA signal 608output from state machine 822 low to disable And gate 604 and TDO3-state buffer 606, which fully decouples bus 406 from bus 518 of FIG.6.

During command bit outputs to command circuit 704, the state machine 822outputs command control (CC) to the command circuit 704 to cause thecommand bits to be input to the command circuit 704. In response to thestop field 716, the state machine 822 stops command bit inputs tocommand circuit 704, transitions to state 818 of FIG. 8B to outputcontrol on CC to cause the command (FPJSEL bus 520 and RPJSEL bus 522)to be output from the command circuit 704. Also in state 818, the statemachine 822 sets the ENA signal 608 high to enable And gate 604 and TDO3-state buffer 606 of FIG. 6 to fully couple busses 406 and 518.

In response to a low on TRST of JTAG bus 406, the state machine 822, TAPstate monitor 824, address circuit 706, and command circuit 704 arereset. Also in response to the RST input 827 from TAP state monitor 824the state machine 822, address circuit 706, and command circuit 704 arereset.

FIG. 8D illustrates an example implementation 828 of the address circuit706, which comprises a shift register 830, update register 832,comparator 834, and device address 836. The shift register 830 receivesthe address bit input (AI) and an A-Clock input from state machine 822.The A-clock input is a signal on the AC bus and is used to clock in theaddress bits from the AI input during state 812 of FIG. 8B. The updateregister 832 inputs the parallel address output from shift register 830in response to an A-Update signal from the AC bus. The update register832 outputs the updated address to comparator 834 during state 814 ofFIG. 8B. The comparator compares the address output from the updateregister to the device address 836. If the addresses match, the Matchsignal from the comparator is set high. If the addresses do not match,the Match signal from the comparator is set low.

In response to a reset output from state machine 822 on the AC bus, as aresult of the state machine receiving a low on the TRST or RST input,the update register 832 is reset to an address value that will not matchthe device address 836.

FIG. 8E illustrates an example implementation 838 of the command circuit704, which comprises a shift register 840 and an update register 842.The shift register 840 receives the command bit inputs (CI) and aC-Clock input from state machine 822. The C-clock input is a signal onthe CC bus and is used to clock in the command bits from the CI inputduring state 816 of FIG. 8B. The update register 842 inputs the parallelcommand output from shift register 840 in response to a C-Update signalfrom the CC bus during state 818 of FIG. 8B. The update register 842outputs the updated command to the FPJSEL bus 520 and RPJSEL bus 522.

In response to a reset output from state machine 822 on the CC bus, as aresult of the state machine receiving a low on the TRST or RST input,the update register 842 is reset to a value where the FPJSEL bus 520does not select an FPJ device group and the RPJSEL bus 522 does notselect a RPJ device group. Also in response to a TRST or RST input, thestate machine sets the ENA signal 608 low to decouple busses 406 and 518of FIG. 6.

FIG. 9 illustrates the FPJ interface 504 of FIG. 5 in more detail. TheFPJ interface comprises an FPJ bus linking circuit 902 and a TDO 3-statebuffer 904. The linking circuit 902 is coupled to the JTAG bus 518 andthe FPJSEL bus 520 from the addressable JTAG interface circuit 502 andto FPJ device groups 410 via one or more JTAG busses 308. The controlinput of the TDO 3-state buffer 904 is coupled to a signal from theFPJSEL bus 520.

In response to an FPJ selection input on FPJSEL bus 520, and when onlyone FPJ device group 410 is being accessed, the linking circuit 902couples bus 518 to a selected bus 308 such that; TDI of bus 518 drivesTDI of selected bus 308, TCK of bus 518 drives TCK of selected bus 308,TMS of bus 518 drives TMS of selected bus 308, and TDO of selected bus308 drives TDO of bus 518, via the TDO 3-state buffer 904.

In response to an FPJ selection input on FPJSEL bus 520, and when afirst and a second FPJ device group 410 are being accessed in adaisy-chain, the linking circuit 902 couples bus 518 to the selectedfirst and second FPJ device groups 410, via their busses 308, such that;TDI of bus 518 drives TDI of the first selected bus 308, TCK of bus 518drives TCK of both first and second selected busses 308, TMS of bus 518drives TMS of both first and second selected busses 308, TDO of thefirst selected bus 308 drives TDI of the second select bus 308, and TDOof the second selected bus 308 drives TDO of bus 518, via the TDO3-state buffer 904.

The daisy-chaining of more than two FPJ device groups 410 is achieved bysimply inputting control on FPJSEL bus 520 to select more than two FPJdevice groups 410, which couples TCK and TMS of bus 518 to all theselected FPJ device groups 410 via their busses 308, daisy-chains theTDI of bus 518 to the TDI of the first FPJ device group 410 via its bus308, forms TDO to TDI couplings between each intermediate FPJ devicegroup 410 via their busses 308, and finally coupling the TDO of the lastselected FPG device group 410 to the TDO of bus 518 via TDO 3-statebuffer 904.

FIG. 10 illustrates the RPJ interface 506 of FIG. 5 in more detail. TheRPJ interface comprises a FPJ to RPJ adapter circuit 1002, a RPJ busselector circuit 1004, and a TDO 3-state buffer 1006. The adaptercircuit 1002 is coupled to the JTAG bus 518 and the RPJSEL bus 522 fromthe addressable JTAG interface circuit 502 and to the RPJ bus selectorcircuit 1004 via an RPJ I/O bus 312. The RPJ bus selector 1004 iscoupled to the RPJSEL bus 522 and to one or more RPJ I/IO busses 312.The control input of the TDO 3-state buffer 1006 is coupled to a signalfrom the RPJSEL bus 522.

In response to an RPJ selection input on RPJSEL bus 522 the adaptercircuit 1002 and buffer 1006 are enabled and the bus selector circuit1004 couples the I/O bus 312 from adapter circuit 1002 to a selected I/Obus 312 coupled to a RPJ device group 412. Non-selected I/O busses 312from selector circuit 1004 are not coupled to I/O bus 312 from adaptercircuit 1002. Following the RPJ selection input on RPJSEL bus 522, theselected RPJ device group 412 may be access by the JTAG bus 518 via theadapter circuit 1002 and selector circuit 1004. During the access, theadapter circuit 1002 operates to convert the JTAG protocol on bus 518into an RPJ protocol such that RPJ interface 506 can communicate withthe selected RPJ device group 412 via selector circuit 1004.

FIG. 10A illustrates an example RPJ interface 506 for communicating withthe previously mentioned SBT based RPJ devices of FIG. 2A. In thisexample the adapter circuit 1002 is designed to convert the JTAGprotocol on bus 518 into the two signal (CLK & DIO) SBT based protocolon bus 312 for communicating with a selected SBT based RPJ device group412 via selector 1004. An example SBT based adapter 1002 is described inthe referenced Whetsel paper. In this example, the SBT based RPJ busselector 1004 is designed to couple the selected SBT based bus 312 of anSBT based device group 412 to the SBT based bus 312 from adapter 1002.

FIG. 10B illustrates an example RPJ interface 506 for communicating withthe previously mentioned IEEE P1149.7 RPJ devices of FIG. 2B. In thisexample the adapter circuit 1002 is designed to convert the JTAGprotocol on bus 518 into the two signal (TCK & TMSC) P1149.7 protocol onbus 312 for communicating with a selected P1149.7 RPJ device group 412via selector 1004. An example P1149.7 adapter 1002 is described in thereferenced P1149.7 white paper. In this example, the P1149.7 RPJ busselector 1004 is designed to couple the selected P1149.7 bus 312 of aP1149.7 device group 412 to the P1149.7 bus 312 from adapter 1002.

FIG. 10C illustrates an example RPJ interface 506 for communicating withthe previously mentioned JLINK RPJ devices of FIG. 2C. In this examplethe adapter circuit 1002 is designed to convert the JTAG protocol on bus518 into the single signal JLINK protocol on bus 312 for communicatingwith a selected JLINK RPJ device 412 via selector 1004. An example JLINKadapter 1002 is described on the referenced JLINK website. In thisexample, the JLINK RPJ bus selector 1004 is designed to couple theselected JLINK bus 312 of a JLINK device 412 to the JLINK bus 312 fromadapter 1002.

FIG. 10D illustrates an example RPJ interface 506 for communicating withthe previously mentioned SWJ RPJ devices of FIG. 2D. In this example theadapter circuit 1002 is designed to convert the JTAG protocol on bus 518into the single signal SWJ protocol on bus 312 for communicating with aselected SWJ RPJ device 412 via selector 1004. An example SWJ adapter1002 is described on the referenced ARM website. In this example, theSWJ RPJ bus selector 1004 is designed to couple the selected SWJ bus 312of a SWJ device 412 to the SWJ bus 312 from adapter 1002.

While FIGS. 10A-10D have shown how the RPJ interface 506 can communicatewith four known types of RPJ device interfaces, it is not limited tocommunicating with only these four RPJ device interfaces. In general,the adapter 1002 and selector 1004 of the RPJ interface 506 can bedesigned to interface to any type of RPJ device interfaces.

FIG. 11 illustrates the JTAG access architecture 1102 of the disclosureadapted for only selecting FPJ device groups 410. As seen, the onlydifference between the architecture of FIG. 11 and FIG. 4 is that theFJP & RPJ Interface circuit 408 of FIG. 4 has been replaced with an FPJOnly Interface circuit 1104 in FIG. 11.

FIG. 12 illustrates in more detail the FPJ Only Interface 1104 of FIG.11. As seen, the FPJ Only Interface 1104 comprises the previouslydescribed FPJ Interface 504 and a modified addressable JTAG interface1202. The addressable JTAG interface 1202 is identical to theaddressable JTAG interface 502 with the exception that the SELRPJ bus522 and associated circuitry has been removed from shadow protocolcircuit 602 of FIG. 6, the command circuit 704 of FIG. 7, and updateregister 842 of FIG. 8 e. The procedure of selecting an FPJ device group410 for access is the same as previously described.

FIG. 13 illustrates the JTAG access architecture 1302 of the disclosureadapted for only selecting RPJ device groups 412. As seen, the onlydifference between the architecture of FIG. 13 and FIG. 4 is that theFJP & RPJ Interface circuit 408 of FIG. 4 has been replaced with an RPJOnly Interface circuit 1304 in FIG. 13.

FIG. 14 illustrates in more detail the RPJ Only Interface 1304 of FIG.13. As seen, the RPJ Only Interface 1304 comprises the previouslydescribed RPJ Interface 506 and a modified addressable JTAG interface1402. The addressable JTAG interface 1402 is identical to theaddressable JTAG interface 502 with the exception that the SELFPJ bus520 and associated circuitry has been removed from shadow protocolcircuit 602 of FIG. 6, the command circuit 704 of FIG. 7, and updateregister 842 of FIG. 8 e. The procedure of selecting a RPJ device group412 for access is the same as previously described.

FIG. 15 is provided to illustrate a system 1502 comprising multipleboards 1504, each board 1504 including either the FPJ and RPJ deviceaccess architecture of FIG. 4, the FPJ Only device access architectureof FIG. 11, or the RPJ Only device access architecture of FIG. 13 toprovide for a JTAG controller 404 to access FPJ and/or RPJ interfaces ofICs on the board 1104 via bus 406.

FIG. 16 is provided to illustrate a board 1602 comprising multiple ICs1604, each IC 1604 including either the FPJ and RPJ device accessarchitecture of FIG. 4, the FPJ Only device access architecture of FIG.11, or the RPJ Only device access architecture of FIG. 13 to provide fora JTAG controller 404 to access FPJ and/or RPJ interfaces of embeddedcores within each IC 1604 via bus 406.

FIG. 17 is provided to illustrate an IC 1702 comprising multipleembedded cores 1704, each embedded core 1704 including either FPJ andRPJ device access architecture of Figure, the FPJ Only device accessarchitecture of FIG. 11, or the RPJ Only device access architecture ofFIG. 13 to provide for a JTAG controller 404 to access FPJ and/or RPJinterfaces of further embedded cores within each embedded core 1704 viabus 406.

FIG. 18 is provided to illustrate how the FPJ and RPJ device accessarchitecture 402 of FIG. 4 may be adapted to provide for wirelesstransmit 1810 and receive 1812 communication with the adaptedarchitecture 1802 of FIG. 18 from a wireless JTAG controller 1804. TheFPJ and RPJ access architecture 1802 is the same as the FPJ and RPJaccess architecture 402 of FIG. 4 with the exception that an RFtransmit/receive circuit 1806 has been coupled to bus 406 of the FJJ &RPJ Interface 408 to provide for wireless communication with thewireless JTAG controller 1804. The wireless JTAG controller 1804 is thesame as the JTAG controller 404 of FIG. 4 with the exception that an RFtransmit/receiver circuit 1808 has been coupled to bus 406 of the JTAGcontroller 404 to provide the wireless communication with the RFtransmit/receive circuit 1806 of FPJ and RPJ access architecture 1802.With the exception of the wireless communication, the operation of thewireless JTAG controller 1804 and wireless FPJ and RPJ device accessarchitecture 1802 is the same as previously described.

FIG. 19 is provided to illustrate how the FPJ Only device accessarchitecture 1102 of FIG. 11 may be adapted to provide for wirelesstransmit 1810 and receive 1812 communication with the adaptedarchitecture 1902 of FIG. 19 from a wireless JTAG controller 1804. TheFPJ Only access architecture 1902 is the same as the FPJ Only accessarchitecture 1102 of FIG. 11 with the exception that an RFtransmit/receive circuit 1806 has been coupled to bus 406 of the FPJOnly Interface 1104 to provide for wireless communication with thewireless JTAG controller 1804. The wireless JTAG controller 1804 is thesame as described in regard to FIG. 18. With the exception of thewireless communication, the operation of the wireless JTAG controller1804 and wireless FPJ Only device access architecture 1902 is the sameas previously described.

FIG. 20 is provided to illustrate how the RPJ Only device accessarchitecture 1302 of FIG. 13 may be adapted to provide for wirelesstransmit 1810 and receive 1812 communication with the adaptedarchitecture 2002 of FIG. 20 from a wireless JTAG controller 1804. TheRPJ Only access architecture 2002 is the same as the RPJ Only accessarchitecture 1302 of FIG. 13 with the exception that an RFtransmit/receive circuit 1806 has been coupled to bus 406 of the RPJOnly Interface 1304 to provide for wireless communication with thewireless JTAG controller 1804. The wireless JTAG controller 1804 is thesame as described in regard to FIG. 18. With the exception of thewireless communication, the operation of the wireless JTAG controller1804 and wireless RPJ Only device access architecture 2002 is the sameas previously described.

Various wireless JTAG access schemes are known in the art. One exampleof wireless JTAG access is described in a paper published in the 2004VLSI Test Symposium proceedings by Hans Eberle, titled “Testing SystemsWirelessly,” which is incorporated and referenced herein. The wirelessinterface circuits 1806 and 1808 for FIGS. 18, 19, and 20 could use thewireless interface described in this paper, or any other type ofwireless JTAG interface.

FIG. 18 illustrates the combined use of a wireless interface and the FPJand RPJ access architecture to wirelessly select and access FPJ and RPJdevices on a substrate.

FIG. 19 illustrates the combined use of a wireless interface and the FPJOnly access architecture to wirelessly select and access FPJ devices ona substrate.

FIG. 20 illustrates the combined use of a wireless interface and the RPJOnly access architecture to wirelessly select and access RPJ devices ona substrate.

Although the disclosure has been described in detail, it should beunderstood that various changes, substitutions and alterations may bemade without departing from the spirit and scope of the disclosure asdefined by the appended claims.

1. A shadow protocol circuit comprising: A. a shadow protocol detectioncircuit having a test data in input, a test clock input, a test modeselect input, an enable output, a command output, a command controloutput, a match input, an address output, and an address control output;B. a command circuit having a command input connected to the commandoutput, a command control input connected to the command control output,a full pin select output, and a reduced pin select output; and C. anaddress circuit having a match output connected to the match input, anaddress input connected to the address output, and an address controlinput connected to the address control output.
 2. The shadow protocolcircuit of claim 1 including a mode gate having one input connected tothe test mode select input, and another input connected to the enableoutput.
 3. The shadow protocol circuit of claim 1 including a tri-stategate having one input connected to a test data out lead, an outputconnected to a gated test data out lead, and a control input connectedto the enable output.